Generated from astext.c with ROBODoc v3.2.3 on Mon Feb 18 01:16:12 2002
NAME
Tutorial 7: Text rendering.
SYNOPSIS
libAfterImage application for rendering texturized text.
DESCRIPTION
In this tutorial we will attempt to render arbitrary text in window,
with optional texturized background and foreground. We shall also
surround rendered text with beveled frame, creating an illusion of a
button.
New steps described in this tutorial are :
ASText.1. Openning and closing fonts.
ASText.2. Approximating rendered text size.
ASText.3. Rendering texturized text.
ASText.4. Merging foreground and background with bevel.
SEE ALSO
Tutorial 1: ASView - explanation of basic steps needed to use
libAfterImage and some other simple things.
Tutorial 2: ASScale - image scaling basics.
Tutorial 3: ASTile - image tiling and tinting.
Tutorial 4: ASMerge - scaling and blending of arbitrary number of
images.
Tutorial 5: ASGrad - drawing multipoint linear gradients.
Tutorial 6: ASFlip - image rotation.
SOURCE
#include <libAfterImage/afterbase.h>
#include <libAfterImage/afterimage.h>
#include "common.h"
/* Usage: astext [-f font] [-s size] [-t text] [-S 3D_style]
[-c text_color] [-b background_color]
[-T foreground_texture] [-B background_image]
[-r foreground_resize_type] [-R background_resize_type]
*/
#define BEVEL_HI_WIDTH 20
#define BEVEL_LO_WIDTH 30
#define BEVEL_ADDON (BEVEL_HI_WIDTH+BEVEL_LO_WIDTH)
void usage()
{
printf( " Usage: astext [-h] [-f font] [-s size] [-t text] [-S 3D_style] \n");
printf( " [-c text_color] [-b background_color]\n");
printf( " [-T foreground_texture] [-B background_image]\n");
printf( " [-r foreground_resize_type] [-R background_resize_type]\n");
printf( " Where: font - TrueType font's filename or X font spec or alias;\n");
printf( " size - size in points for TrueType fonts;\n");
printf( " text - text to be drawn;\n");
printf( " 3D_style - 3D style of text. One of the following:\n");
printf( " 0 - plain 2D tetx, 1 - embossed, 2 - sunken, 3 - shade above,\n");
printf( " 4 - shade below, 5 - embossed thick 6 - sunken thick.\n");
printf( " resize_type - tells how texture/image should be transformed to fit\n");
printf( " the text size. Could be: scale or tile. Default is tile\n");
}
int main(int argc, char* argv[])
{
ASVisual *asv = NULL ;
int screen = 0, depth = 0;
char *font_name = "test.ttf";
int size = 32 ;
char *text = "Smart Brown Dog jumps\nOver The Lazy Fox,\nand falls into the ditch.";
ARGB32 text_color = ARGB32_White, back_color = ARGB32_Black;
char *text_color_name = "#FFFFFFFF", *back_color_name = "#FF000000";
char *fore_image_file = "fore.xpm", *back_image_file = "back.xpm" ;
Bool scale_fore_image = False, scale_back_image = False ;
ASImage *fore_im = NULL, *back_im = NULL;
ASImage *text_im = NULL ;
ASText3DType type_3d = AST_ShadeBelow ;
struct ASFontManager *fontman = NULL;
struct ASFont *font = NULL;
unsigned int width, height ;
int i ;
int text_margin = size/2 ;
/* see ASView.1 : */
set_application_name( argv[0] );
#if (HAVE_AFTERBASE_FLAG==1)
set_output_threshold(OUTPUT_LEVEL_DEBUG);
#endif
if( argc == 1 )
usage();
else for( i = 1 ; i < argc ; i++ )
{
if( strncmp( argv[i], "-h", 2 ) == 0 )
{
usage();
return 0;
}
if( i+1 < argc )
{
if( strncmp( argv[i], "-f", 2 ) == 0 )
font_name = argv[i+1] ;
else if( strncmp( argv[i], "-s", 2 ) == 0 )
{
size = atoi(argv[i+1]);
text_margin = size/2 ;
}else if( strncmp( argv[i], "-t", 2 ) == 0 )
text = argv[i+1] ;
else if( strncmp( argv[i], "-S", 2 ) == 0 )
{
type_3d = atoi(argv[i+1]);
if( type_3d >= AST_3DTypes )
{
show_error( "3D type is wrong. Using 2D Plain instead.");
type_3d = AST_Plain ;
}
}else if( strncmp( argv[i], "-c", 2 ) == 0 )
text_color_name = argv[i+1] ;
else if( strncmp( argv[i], "-b", 2 ) == 0 )
back_color_name = argv[i+1] ;
else if( strncmp( argv[i], "-T", 2 ) == 0 )
fore_image_file = argv[i+1] ;
else if( strncmp( argv[i], "-B", 2 ) == 0 )
back_image_file = argv[i+1] ;
else if( strncmp( argv[i], "-r", 2 ) == 0 )
scale_fore_image = (strcmp( argv[i+1], "scale") == 0);
else if( strncmp( argv[i], "-R", 2 ) == 0 )
scale_back_image = (strcmp( argv[i+1], "scale") == 0);
}
}
#ifndef X_DISPLAY_MISSING
dpy = XOpenDisplay(NULL);
_XA_WM_DELETE_WINDOW = XInternAtom( dpy, "WM_DELETE_WINDOW", False);
screen = DefaultScreen(dpy);
depth = DefaultDepth( dpy, screen );
#endif
/* see ASText.1 : */
if( (fontman = create_font_manager( dpy, NULL, NULL )) != NULL )
font = get_asfont( fontman, font_name, 0, size, ASF_GuessWho );
if( font == NULL )
{
show_error( "unable to load requested font \"%s\". Falling back to \"fixed\".", font_name );
font = get_asfont( fontman, "fixed", 0, size, ASF_GuessWho );
if( font == NULL )
{
show_error( "font \"fixed\" is not available either. Aborting.");
return 1;
}
}
parse_argb_color( text_color_name, &text_color );
parse_argb_color( back_color_name, &back_color );
/* see ASView.3 : */
asv = create_asvisual( dpy, screen, depth, NULL );
/* see ASText.2 : */
/*set_asfont_glyph_spacing( font, 10, 40 );*/
get_text_size( text, font, type_3d, &width, &height );
if( fore_image_file )
{
ASImage *tmp = file2ASImage( fore_image_file, 0xFFFFFFFF,
SCREEN_GAMMA, 0, NULL );
if( tmp )
{
if( tmp->width != width || tmp->height != height )
{ /* see ASScale.2 : */
if( scale_fore_image )
fore_im = scale_asimage( asv, tmp, width, height,
ASA_ASImage, 0, ASIMAGE_QUALITY_DEFAULT );
else
fore_im = tile_asimage( asv, tmp, 0, 0, width, height, 0,
ASA_ASImage, 0, ASIMAGE_QUALITY_DEFAULT );
destroy_asimage( &tmp );
}else
fore_im = tmp ;
}
}
width += text_margin*2 + BEVEL_ADDON;
height += text_margin*2 + BEVEL_ADDON;
if( back_image_file )
{ /* see ASView.2 : */
ASImage *tmp = file2ASImage( back_image_file, 0xFFFFFFFF,
SCREEN_GAMMA, 0, NULL );
if( tmp )
{
if( scale_back_image && (tmp->width != width || tmp->height != height) )
{ /* see ASScale.2 : */
back_im = scale_asimage( asv, tmp, width, height,
ASA_ASImage, 0, ASIMAGE_QUALITY_DEFAULT );
destroy_asimage( &tmp );
}else
back_im = tmp ;
}
}
/* see ASText.3 : */
text_im = draw_text( text, font, type_3d, 0 );
if( fore_im )
{
move_asimage_channel( fore_im, IC_ALPHA, text_im, IC_ALPHA );
destroy_asimage( &text_im );
}else
fore_im = text_im ;
/* see ASText.1 : */
release_font( font );
destroy_font_manager( fontman, False );
if( fore_im )
{
ASImage *rendered_im ;
ASImageLayer layers[2] ;
ASImageBevel bevel = {0/*BEVEL_SOLID_INLINE*/, 0xFFDDDDDD, 0xFF555555, 0xFFFFFFFF, 0xFF777777, 0xFF222222,
BEVEL_HI_WIDTH, BEVEL_HI_WIDTH,
BEVEL_LO_WIDTH, BEVEL_LO_WIDTH,
BEVEL_HI_WIDTH, BEVEL_HI_WIDTH,
BEVEL_LO_WIDTH, BEVEL_LO_WIDTH } ;
/* see ASText.4 : */
init_image_layers( &(layers[0]), 2 );
back_im->back_color = back_color ;
fore_im->back_color = text_color ;
layers[0].im = back_im ;
layers[0].dst_x = 0 ;
layers[0].dst_y = 0 ;
layers[0].clip_width = width ;
layers[0].clip_height = height ;
layers[0].bevel = &bevel ;
layers[1].im = fore_im ;
layers[1].dst_x = text_margin+BEVEL_HI_WIDTH*2 ;
layers[1].dst_y = text_margin+MIN((int)text_margin,((int)font->max_height-(int)font->max_ascend))/2+BEVEL_HI_WIDTH*2;
layers[1].clip_width = fore_im->width ;
layers[1].clip_height = fore_im->height ;
rendered_im = merge_layers( asv, &(layers[0]), 2,
width+BEVEL_ADDON, height+BEVEL_ADDON,
#ifndef X_DISPLAY_MISSING
ASA_XImage,
#else
ASA_ASImage,
#endif
0, ASIMAGE_QUALITY_DEFAULT);
destroy_asimage( &fore_im );
destroy_asimage( &back_im );
if( rendered_im )
{
#ifndef X_DISPLAY_MISSING
Window w;
/* see ASView.4 : */
w = create_top_level_window( asv, DefaultRootWindow(dpy), 32, 32,
width+BEVEL_ADDON, height+BEVEL_ADDON,
1, 0, NULL,
"ASText" );
if( w != None )
{
Pixmap p ;
XMapRaised (dpy, w);
/* see ASView.5 : */
p = asimage2pixmap( asv, DefaultRootWindow(dpy), rendered_im,
NULL, True );
destroy_asimage( &rendered_im );
/* see common.c: set_window_background_and_free() : */
p = set_window_background_and_free( w, p );
/* see common.c: wait_closedown() : */
wait_closedown(w);
}
if( dpy )
XCloseDisplay (dpy);
#else
/* writing result into the file */
ASImage2file( rendered_im, NULL, "astext.jpg", ASIT_Jpeg, NULL );
destroy_asimage( &rendered_im );
#endif
}
}
return 0 ;
}
SYNOPSIS
Step 1. Openning and closing fonts.
DESCRIPTION
Before any text can be rendered using libAfterImage - desired font
has to be opened for use. Font opening process is two-step. At first
we need to create font manager ( ASFontManager ). That is done once,
and same font manger can be used throughout entire application. It
contains information about used external libraries, hash of opened
fonts, and some other info.
When ASFontManager is created it could be used to obtain actuall fonts.
get_asfont() call is used to query cahce of the ASFontManager, to see
if the font has been loaded already, and if not - then it will load
the font and prepare it for drawing.
EXAMPLE
if( (fontman = create_font_manager( dpy, NULL, NULL )) != NULL )
font = get_asfont( fontman, font_name, 0, size, ASF_GuessWho);
if( font == NULL )
{
font = get_asfont( fontman, "fixed", 0, size, ASF_GuessWho );
if( font == NULL )
{
show_error( "font \"fixed\" is not available either. Aborting.");
return 1;
}
}
...
destroy_font( font );
destroy_font_manager( fontman, False );
SEE ALSO
create_font_manager(), get_asfont(), destroy_font(),
destroy_font_manager()
SYNOPSIS
Step 2. Approximating rendered text size.
DESCRIPTION
Prior to actually drawing the text it is usefull to estimate the size
of the image, that rendered text will occupy, So that window can be
created of appropriate size, and othe interface elements laid out
accordingly. get_text_size() could be used to obtain rendered text
size without actually drawing it.
EXAMPLE
get_text_size( text, font, type_3d, &width, &height );
if( fore_image_file )
{
ASImage *tmp = file2ASImage( fore_image_file, 0xFFFFFFFF,
SCREEN_GAMMA, 0, NULL );
if( tmp )
{
if( tmp->width != width || tmp->height != height )
{
if( scale_fore_image )
fore_im = scale_asimage( asv, tmp, width, height,
ASA_ASImage, 0,
ASIMAGE_QUALITY_DEFAULT );
else
fore_im = tile_asimage( asv, tmp, 0, 0,
width, height, 0,
ASA_ASImage, 0,
ASIMAGE_QUALITY_DEFAULT );
destroy_asimage( &tmp );
}else
fore_im = tmp ;
}
}
NOTES
In this particular example we either tile or scale foreground texture
to fit the text. In order to texturize the text - we need to use
rendered text as an alpha channel on texture image. That can easily
be done only if both images are the same size.
SEE ALSO
get_text_size(), scale_asimage(), tile_asimage(), ASText.3
SYNOPSIS
Step 3. Rendering texturized text.
DESCRIPTION
The most effective text texturization technique provided by
libAfterImage consists of substitution of the alpha channel of the
texture, with rendered text. That is possible since all the text is
rendered into alpha channel only. move_asimage_channel() call is used
to accomplish this operation. This call actually removes channel
data from the original image and stores it in destination image. If
there was something in destination image's channel already - it will
be destroyed.
All kinds of nifty things could be done using this call, actually.
Like, for example, rendered text can be moved into green channel of
the texture, creating funky effect.
EXAMPLE
text_im = draw_text( text, font, 0 );
if( fore_im )
{
move_asimage_channel( fore_im, IC_ALPHA, text_im, IC_ALPHA );
destroy_asimage( &text_im );
}else
fore_im = text_im ;
NOTES
move_asimage_channel() will only work if both images have exactly the
same size. It will do nothing otherwise.
SEE ALSO
draw_text(), move_asimage_channel()
SYNOPSIS
Step 4. Merging foreground and background with bevel.
DESCRIPTION
On this step we have 2 images ready for us - background and texturized
text. At this point we need to merge them together by alpha-blending
text over background (remeber - text is alpha-channel of foreground
texture). At the same time we would like to add some nice bevel border
around entire image. To accomplish that task all we have to do is setup
ASImageLayer structure for both background and foreground, and apply
merge_layers on them. When it is done - we no longer need original
images and we destroy them to free up some memory.
EXAMPLE
ASImageLayer layers[2] ;
ASImageBevel bevel = {0, 0xFFDDDDDD, 0xFF555555,
0xFFFFFFFF, 0xFF777777, 0xFF444444,
BEVEL_HI_WIDTH, BEVEL_HI_WIDTH,
BEVEL_LO_WIDTH, BEVEL_LO_WIDTH,
BEVEL_HI_WIDTH, BEVEL_HI_WIDTH,
BEVEL_LO_WIDTH, BEVEL_LO_WIDTH } ;
memset( &(layers[0]), 0x00, sizeof(layers) );
layers[0].im = back_im ;
layers[0].clip_width = width ;
layers[0].clip_height = height ;
layers[0].merge_scanlines = alphablend_scanlines ;
layers[0].bevel = &bevel ;
layers[1].im = fore_im ;
layers[1].dst_x = TEXT_MARGIN ;
layers[1].dst_y = TEXT_MARGIN ;
layers[1].clip_width = fore_im->width ;
layers[1].clip_height = fore_im->height ;
layers[1].back_color = text_color ;
layers[1].merge_scanlines = alphablend_scanlines ;
rendered_im = merge_layers( asv, &(layers[0]), 2,
width+BEVEL_ADDON, height+BEVEL_ADDON,
ASA_XImage, 0, ASIMAGE_QUALITY_DEFAULT);
destroy_asimage( &fore_im );
destroy_asimage( &back_im );
NOTES
We have to remember that outside bevel border will addup to the image
size, hence we have to use width+BEVEL_ADDON , height+BEVEL_ADDON as
desired image size.
SEE ALSO
ASImageLayer, ASImageBevel, merge_layers()